Pyridine derivatives as H3 antagonists

ABSTRACT

The present invention relates to compounds of formula I 
                         
wherein R 1 , R 2  and A are as defined in the description and claims, and pharmaceutically acceptable salts thereof as well as to pharmaceutical composition comprising these compounds and to methods for their preparation. The compounds are useful for the treatment and/or prevention of diseases which are associated with the modulation of H3 receptors.

PRIORITY TO RELATED APPLICATIONS

This application claims the benefit of European Application No. 04106265.4 filed Dec. 3, 2004, which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention is directed to novel 3-substituted 6-piperazinyl-pyridine derivatives, their manufacture, pharmaceutical compositions containing them and their use as medicaments. The active compounds of the present invention are useful in treating obesity and other disorders.

In a preferred embodiment, the present invention is directed to compounds of the general formula

and pharmaceutically acceptable salts thereof.

It has been found that the compounds of formula I are antagonists and/or inverse agonists at the histamine 3 receptor (H3 receptor).

All documents cited or relied upon below are expressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

Histamine (2-(4-imidazolyl) ethylamine) is one of the aminergic neurotransmitters which is widely distributed throughout the body, e.g. the gastrointestinal tract (Burks 1994 in Johnson L. R. ed., Physiology of the Gastrointestinal Tract, Raven Press, NY, pp. 211-242). Histamine regulates a variety of digestive pathophysiological events like gastric acid secretion, intestinal motility (Leurs et al., Br J. Pharmacol. 1991, 102, pp 179-185), vasomotor responses, intestinal inflammatory responses and allergic reactions (Raithel et al., Int. Arch. Allergy Immunol. 1995, 108, 127-133). In the mammalian brain, histamine is synthesized in histaminergic cell bodies which are found centrally in the tuberomammillary nucleus of the posterior basal hypothalamus. From there, the cell bodies project to various brain regions (Panula et al., Proc. Natl. Acad. Sci. USA 1984, 81, 2572-2576; Inagaki et al., J. Comp. Neurol 1988, 273, 283-300).

According to current knowledge, histamine mediates all its actions in both the CNS and in the periphery through four distinct histamine receptors, the histamine H1, H2, H3 and H4 receptors. H3 receptors are predominantly localized in the central nervous system (CNS). As an autoreceptor, H3 receptors constitutively inhibit the synthesis and secretion of histamine from histaminergic neurons (Arrang et al., Nature 1983, 302, 832-837; Arrang et al., Neuroscience 1987, 23, 149-157). As heteroreceptors, H3 receptors also modulate the release of other neurotransmitters such as acetylcholine, dopamine, serotonin and norepinephrine among others in both the central nervous system and in peripheral organs, such as lungs, cardiovascular system and gastrointestinal tract (Clapham & Kilpatrik, Br. J. Pharmacol. 1982, 107, 919-923; Blandina et al. in The Histamine H3 Receptor (Leurs R L and Timmermann H eds, 1998, pp 27-40, Elsevier, Amsterdam, The Netherlands). H3 receptors are constitutively active, meaning that even without exogenous histamine, the receptor is tonically activated. In the case of an inhibitory receptor such as the H3 receptor, this inherent activity causes tonic inhibition of neurotransmitter release. Therefore it may be important that a H3R antagonist would also have inverse agonist activity to both block exogenous histamine effects and to shift the receptor from its constitutively active (inhibitory) form to a neutral state.

The wide distribution of H3 receptors in the mammalian CNS indicates the physiological role of this receptor. Therefore the therapeutic potential as a novel drug development target in various indications has been proposed.

The administration of H3R ligands—as antagonists, inverse agonists, agonists or partial agonists may influence the histamine levels or the secretion of neurotransmitters in the brain and the periphery and thus may be useful in the treatment of several disorders. Such disorders include obesity, (Masaki et al; Endocrinol. 2003, 144, 2741-2748; Hancock et al., European J. of Pharmacol. 2004, 487, 183-197), cardiovascular disorders such as acute myocardial infarction, dementia and cognitive disorders such as attention deficit hyperactivity disorder (ADHD) and Alzheimer's disease, neurological disorders such as schizophrenia, depression, epilepsy, Parkinson's disease, and seizures or convulsions, sleep disorders, narcolepsy, pain, gastrointestinal disorders, vestibular dysfunction such as Morbus Meniere, drug abuse and motion sickness (Timmermann, J. Med. Chem. 1990, 33, 4-11).

SUMMARY OF THE INVENTION

In one embodiment of the present invention, provided is a compound of the formula I:

wherein:

-   R¹ is selected from the group consisting of hydrogen, lower alkyl,     C₃-C₇-alkenyl, C₃-C₇-alkinyl, lower halogenalkyl, lower     hydroxyalkyl, lower alkoxyalkyl, C₃-C₇-cycloalkyl, and lower     C₃-C₇-cycloalkylalkyl; -   X is C(O) or SO₂; -   m is 0 or 1; -   R² is selected from the group consisting of lower alkyl,     C₃-C₇-alkenyl, C₃-C₇-alkinyl, lower halogenalkyl, lower     hydroxyalkyl, lower alkoxyalkyl, -   unsubstituted C₃-C₇-cycloalkyl or C₃-C₇-cycloalkyl substituted by     phenyl, lower C₃-C₇-cycloalkylalkyl, -   lower phenylalkyl wherein phenyl is unsubstituted or mono- or     disubstituted by lower alkyl, lower alkoxy, halogen or lower     halogenalkyl, -   unsubstituted pyridyl or pyridyl mono- or disubstituted by lower     alkyl, lower alkoxy, halogen or lower halogenalkyl, and -   —NR³R⁴, -   or, in case X is C(O), R² can also be lower alkoxy or lower     alkoxyalkoxy, -   or, in case m is 1, R² can also be unsubstituted phenyl or phenyl     mono- or disubstituted by lower alkyl, lower alkoxy, halogen or     lower halogenalkyl, -   R³ is hydrogen or lower alkyl; -   R⁴ is selected from the group consisting of lower alkyl,     C₃-C₇-alkenyl, C₃-C₇-alkinyl, lower alkoxyalkyl, -   C₃-C₇-cycloalkyl, -   C₃-C₇-cycloalkyl substituted by phenyl, -   lower C₃-C₇-cycloalkylalkyl, -   unsubstituted phenyl or phenyl mono- or disubstituted by lower     alkyl, lower alkoxy, halogen or lower halogenalkyl, and -   lower phenylalkyl wherein phenyl is unsubstituted or mono- or     disubstituted by lower alkyl, lower alkoxy, halogen or lower     halogenalkyl; or -   R³ and R⁴ together with the nitrogen atom to which they are attached     form a 4-, 5-, 6- or 7-membered heterocyclic ring optionally     containing a further heteroatom selected from nitrogen, oxygen or     sulfur, said heterocyclic ring being unsubstituted or substituted by     one, two or three groups independently selected from lower alkyl,     lower alkoxy, lower alkoxycarbonyl, oxo, halogen and halogenalkyl,     or being condensed with a C₅-C₆-cycloalkyl ring or a phenyl ring,     said cycloalkyl ring or phenyl ring being unsubstituted or     substituted by one, two or three groups independently selected from     lower alkyl, lower alkoxy, halogen and halogenalkyl; -   and pharmaceutically acceptable salts thereof; -   with the exception of     2,2-dimethyl-N-[6-(4-methyl-piperazin-1-yl)-pyridin-3-yl]-propionamide.

In another embodiment of the present invention, provided is a process for the manufacture of a compound according to formula I, comprising the steps of:

-   a) reacting a compound of the formula II

wherein R¹ and m are as defined above,

-   with a sulfonylchloride or sulfamoylchloride of the formula III     R²—SO₂—Cl  III     wherein R² is as defined above, -   to obtain a compound of the formula I-A

wherein R¹, R² and m are as defined above, or

-   b) reacting a compound of the formula II

wherein R¹ and m are as defined above,

-   with a chloride of the formula IV     R²—C(O)Cl  IV     wherein R² is as defined above, -   to obtain a compound of the formula I-B

wherein R¹, R² and m are as defined above, or

-   c) reacting a compound of the formula II

wherein R¹ and m are as defined above,

-   with an isocyanate of the formula V     R⁴—N═C═O  V     wherein R⁴ is as defined above, -   to obtain a compound of the formula I-C

wherein R³ is hydrogen and R¹, R⁴ and m are as defined above,

-   and if desired, converting the compound of formula I-A, I-B or I-C     into a pharmaceutically acceptable salt.

In a further embodiment of the present invention, provided is a pharmaceutical composition, comprising a therapeutically effective amount of a compound according to formula I and a pharmaceutically acceptable carrier and/or adjuvant.

In a still another embodiment of the present invention, provided is a method for the treatment and/or prevention of diseases which are associated with the modulation of H3 receptors, comprising the step of administering a therapeutically effective amount of a compound according to formula I to a human being or animal in need thereof.

DETAILED DESCRIPTION

The present invention provides for selective, directly acting H3 receptor antagonists respectively inverse agonists. Such antagonists/inverse agonists are useful as therapeutically active substances, particularly in the treatment and/or prevention of diseases which are associated with the modulation of H3 receptors.

In the present description the term “alkyl”, alone or in combination with other groups, refers to a branched or straight-chain monovalent saturated aliphatic hydrocarbon radical of one to twenty carbon atoms, preferably one to sixteen carbon atoms, more preferably one to ten carbon atoms.

The term “lower alkyl” or “C₁-C₈-alkyl”, alone or in combination, signifies a straight-chain or branched-chain alkyl group with 1 to 8 carbon atoms, preferably a straight or branched-chain alkyl group with 1 to 6 carbon atoms and particularly preferred a straight or branched-chain alkyl group with 1 to 4 carbon atoms Examples of straight-chain and branched C₁-C₈ alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert.-butyl, the isomeric pentyls, the isomeric hexyls, the isomeric heptyls and the isomeric octyls, preferably methyl, ethyl and isopropyl, and most preferred methyl and ethyl.

The term “lower alkenyl” or “C₃-C₈-alkenyl”, alone or in combination, signifies a straight-chain or branched alkyl group comprising an olefinic bond and up to 8, preferably up to 6, particularly preferred up to 4 carbon atoms. Examples of alkenyl groups are 1-propenyl, 2-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl and isobutenyl. A preferred example is 2-propenyl. The term “lower alkinyl” or “C₃-C₈-alkinyl”, alone or in combination, signifies a straight-chain or branched alkyl group comprising a triple bond and up to 8, preferably up to 6, particularly preferred up to 4 carbon atoms. Examples of alkinyl groups include 2-propinyl (propargyl), 1-methyl-2-propinyl, 2-butinyl, 3-butinyl, 2-pentinyl and 1-pentin-3-yl.

The term “alkoxy” refers to the group R′—O—, wherein R′ is alkyl. The term “lower alkoxy” refers to the group R′—O—, wherein R′ is lower alkyl and the term “lower alkyl” has the previously given significance (“C₁-C₈-alkoxy”). Examples of lower alkoxy groups are e.g. methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec. butoxy and tert.butoxy, preferably methoxy and ethoxy and most preferred methoxy.

The term “lower alkoxyalkyl” or “C₁-C₈-alkoxy-C₁-C₈-alkyl” refers to lower alkyl groups as defined above wherein at least one of the hydrogen atoms of the lower alkyl group is replaced by an alkoxy group as defined above. Among the preferred lower alkoxyalkyl groups are methoxymethyl, methoxyethyl and ethoxymethyl, with methoxymethyl being especially preferred.

The term “lower-alkoxyalkoxy” or “C₁-C₈-alkoxy-C₁-C₈-alkoxy” refers to lower alkoxy groups as defined above wherein at least one of the hydrogen atoms of the lower alkoxy group is replaced by an alkoxy group as defined above. Among the preferred lower alkoxyalkoxy groups are methoxyethoxy, methoxypropyloxy and ethoxyethoxy, with methoxyethoxy being especially preferred.

The term “halogen” refers to fluorine, chlorine, bromine and iodine, with fluorine, chlorine and bromine being preferred.

The term “lower halogenalkyl” or “halogen-C₁-C₈-alkyl” refers to lower alkyl groups as defined above wherein at least one of the hydrogen atoms of the lower alkyl group is replaced by a halogen atom, preferably fluoro or chloro, most preferably fluoro. Among the preferred halogenated lower alkyl groups are trifluoromethyl, difluoromethyl, fluoromethyl and chloromethyl, with trifluoromethyl being especially preferred.

The term “lower hydroxyalkyl” or “hydroxy-C₁-C₈-alkyl” refers to lower alkyl groups as defined above wherein at least one of the hydrogen atoms of the lower alkyl group is replaced by a hydroxy group. Examples of lower hydroxyalkyl groups are hydroxymethyl or hydroxyethyl.

The term “cycloalkyl” or “C₃-C₇-cycloalkyl” means a cycloalkyl ring containing 3 to 7 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl. The cycloalkyl ring may be substituted as defined herein. Especially preferred is cyclopropyl or cyclopentyl.

The term “lower cycloalkylalkyl” or “C₃-C₇-cycloalkyl-C₁-C₈-alkyl” refers to lower alkyl groups as defined above wherein at least one of the hydrogen atoms of the lower alkyl group is replaced by a cycloalkyl group as defined above. Examples of preferred lower cycloalkylalkyl groups are cyclopropylmethyl or cyclopropylmethyl.

The term “lower phenylalkyl” or “phenyl-C₁-C₈-alkyl” refers to lower alkyl groups as defined above wherein at least one of the hydrogen atoms of the lower alkyl group is replaced by a phenyl group. The phenyl ring may be substituted as defined herein. Examples of preferred lower phenylalkyl groups are benzyl, 4-methylbenzyl, 4-fluorobenzyl, 3-methoxybenzyl and 3,4-dimethoxybenzyl.

The term “form a 4-, 5-, 6- or 7-membered saturated heterocyclic ring optionally containing a further heteroatom selected from nitrogen, oxygen or sulfur” refers to a saturated N-heterocyclic ring, which may optionally contain a further nitrogen, oxygen or sulfur atom, such as azetidinyl, pyrrolidinyl, imidazolidinyl, pyrazolidinyl, oxazolidinyl, isoxazolidinyl, thiazolidinyl, isothiazolidinyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, or azepanyl. The heteroyclic ring may be unsubstituted or substituted by one, two or three groups independently selected from lower alkyl, lower alkoxy, oxo, halogen and halogenalkyl. The heterocyclic ring may also be condensed with a C₅-C₆-cycloalkyl ring or a phenyl ring, said cycloalkyl ring or phenyl ring being unsubstituted or substituted by one, two or three groups independently selected from lower alkyl, lower alkoxy, halogen and halogenalkyl. Examples for such a condensed heterocyclic rings are 3,4-dihydro-1H-isoquinoline, 1,3-dihydro-isoindole and octahydroquinoline.

The term “pharmaceutically acceptable salts” refers to those salts which retain the biological effectiveness and properties of the free bases or free acids, which are not biologically or otherwise undesirable. The salts are formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, preferably hydrochloric acid, and organic acids such as acetic acid, propionic acid, glycolic acid, pyruvic acid, oxylic acid, maleic acid, malonic acid, salicylic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid, N-acetylcystein and the like. In addition these salts may be prepared form addition of an inorganic base or an organic base to the free acid. Salts derived from an inorganic base include, but are not limited to, the sodium, potassium, lithium, ammonium, calcium, magnesium salts and the like. Salts derived from organic bases include, but are not limited to salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, ethanolamine, lysine, arginine, N-ethylpiperidine, piperidine, polymine resins and the like. The compound of formula I can also be present in the form of zwitterions. Particularly preferred pharmaceutically acceptable salts of compounds of formula I are the hydrochloride salts.

The compounds of formula I can also be solvated, e.g. hydrated. The solvation can be effected in the course of the manufacturing process or can take place e.g. as a consequence of hygroscopic properties of an initially anhydrous compound of formula I (hydration). The term pharmaceutically acceptable salts also includes physiologically acceptable solvates.

“Isomers” are compounds that have identical molecular formulae but that differ in the nature or the sequence of bonding of their atoms or in the arrangement of their atoms in space. Isomers that differ in the arrangement of their atoms in space are termed “stereoisomers”. Stereoisomers that are not mirror images of one another are termed “diastereoisomers”, and stereoisomers that are non-superimposable mirror images are termed “enantiomers”, or sometimes optical isomers.

A carbon atom bonded to four nonidentical substituents is termed a “chiral center”.

In detail, the present invention relates to compounds of the general formula

wherein

-   R¹ is selected from the group consisting of hydrogen, lower alkyl,     C₃-C₇-alkenyl, C₃-C₇-alkinyl, lower halogenalkyl, lower     hydroxyalkyl, lower alkoxyalkyl, C₃-C₇-cycloalkyl, and lower     C₃-C₇-cycloalkylalkyl; -   X is C(O) or SO₂; -   m is 0 or 1; -   R² is selected from the group consisting of lower alkyl,     C₃-C₇-alkenyl, C₃-C₇-alkinyl, lower halogenalkyl, lower     hydroxyalkyl, lower alkoxyalkyl, -   unsubstituted C₃-C₇-cycloalkyl or C₃-C₇-cycloalkyl substituted by     phenyl, -   lower C₃-C₇-cycloalkylalkyl, -   lower phenylalkyl wherein phenyl is unsubstituted or mono- or     disubstituted by lower alkyl lower alkoxy, halogen or lower     halogenalkyl, -   unsubstituted pyridyl or pyridyl mono- or disubstituted by lower     alkyl, lower alkoxy, halogen or lower halogenalkyl, and -   —NR³R⁴, -   or, in case X is C(O), R² can also be lower alkoxy or lower     alkoxyalkoxy, -   or, in case m is 1, R² can also be unsubstituted phenyl or phenyl     mono- or disubstituted by lower alkyl, lower alkoxy, halogen or     lower halogenalkyl, -   R³ is hydrogen or lower alkyl; -   R⁴ is selected from the group consisting of lower alkyl,     C₃-C₇-alkenyl, C₃-C₇-alkinyl, lower alkoxyalkyl, -   C₃-C₇-cycloalkyl, -   C₃-C₇-cycloalkyl substituted by phenyl, -   lower C₃-C₇-cycloalkylalkyl, -   unsubstituted phenyl or phenyl mono- or disubstituted by lower     alkyl, lower alkoxy, halogen or lower halogenalkyl, and -   lower phenylalkyl wherein phenyl is unsubstituted or mono- or     disubstituted by lower alkyl, lower alkoxy, halogen or lower     halogenalkyl; or -   R³ and R⁴ together with the nitrogen atom to which they are attached     form a 4-, 5-, 6- or 7-membered heterocyclic ring optionally     containing a further heteroatom selected from nitrogen, oxygen or     sulfur, said heterocyclic ring being unsubstituted or substituted by     one, two or three groups independently selected from lower alkyl,     lower alkoxy, lower alkoxycarbonyl, oxo, halogen and halogenalkyl,     or being condensed with a C₅-C₆-cycloalkyl ring or a phenyl ring,     said cycloalkyl ring or phenyl ring being unsubstituted or     substituted by one, two or three groups independently selected from     lower alkyl, lower alkoxy, halogen and halogenalkyl; -   and pharmaceutically acceptable salts thereof; -   with the exception of     2,2-dimethyl-N-[6-(4-methyl-piperazin-1-yl)-pyridin-3-yl]-propionamide.

Thus, the substituent R¹ is selected from the group consisting of hydrogen, lower alkyl, C₃-C₇-alkenyl, C₃-C₇-alkinyl, lower halogenalkyl, lower hydroxyalkyl, lower alkoxyalkyl, C₃-C₇-cycloalkyl and lower C₃-C₇-cycloalkylalkyl. Preferred compounds of formula I according to the present invention are those, wherein R¹ is lower alkyl or C₃-C₇-cycloalkyl, with those compounds, wherein R¹ is C₃-C₇-cycloalkyl being more preferred, and those compounds, wherein R¹ is cyclopentyl, being most preferred. Compounds of formula I, wherein R¹ is ethyl or isopropyl, are also very preferred.

m is an integer of 0 or 1. Especially preferred are those compounds of formula I, wherein m is 1. However, compounds of formula I, wherein m is 0, are also a preferred embodiment of the invention.

Further preferred are compounds of formula I according to the present invention, wherein R² is selected from the group consisting of

-   lower alkyl, C₃-C₇-alkenyl, C₃-C₇-alkinyl, -   lower halogenalkyl, lower hydroxyalkyl, lower alkoxyalkyl, -   unsubstituted C₃-C₇-cycloalkyl or C₃-C₇-cycloalkyl substituted by     phenyl, -   lower C₃-C₇-cycloalkylalkyl, -   lower phenylalkyl wherein phenyl is unsubstituted or mono- or     disubstituted by lower alkyl, lower alkoxy, halogen or lower     halogenalkyl, -   unsubstituted pyridyl or pyridyl mono- or disubstituted by lower     alkyl, lower alkoxy, halogen or lower halogenalkyl, and -   —NR³R⁴, -   or, in case X is C(O), R² can also be lower alkoxy or lower     alkoxyalkoxy.

Within this group, compounds of formula I, wherein R² is selected from the group consisting of lower alkyl, C₃-C₇-cycloalkyl and C₃-C₇-cycloalkyl substituted by phenyl, are preferred.

Furthermore, compounds of formula I are preferred, wherein R² is lower phenylalkyl wherein phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl.

Also preferred are compounds of formula I of the present invention, wherein R² is the group —NR³R⁴.

More preferred are those compounds of formula I, wherein R² is the group —NR³R⁴ and R³ is hydrogen or lower alkyl;

-   R⁴ is selected from the group consisting of lower alkyl,     C₃-C₇-alkenyl, C₃-C₇-alkinyl, C₃-C₇-cycloalkyl, -   C₃-C₇-cycloalkyl substituted by phenyl, -   lower C₃-C₇-cycloalkylalkyl, -   unsubstituted phenyl or phenyl mono- or disubstituted by lower     alkyl, lower alkoxy, halogen or lower halogenalkyl, and -   lower phenylalkyl wherein phenyl is unsubstituted or mono- or     disubstituted by lower alkyl, lower alkoxy, halogen or lower     halogenalkyl; or -   R³ and R⁴ together with the nitrogen atom to which they are attached     form a 4-, 5-, 6- or 7-membered heterocyclic ring optionally     containing a further heteroatom selected from nitrogen, oxygen or     sulfur, said heterocyclic ring being unsubstituted or substituted by     one, two or three groups independently selected from lower alkyl,     lower alkoxy, oxo, halogen and halogenalkyl, or being condensed with     a phenyl ring, said phenyl ring being unsubstituted or substituted     by one, two or three groups independently selected from lower alkyl,     lower alkoxy, halogen and halogenalkyl.

Especially preferred are those compounds of formula I, wherein R³ and R⁴ are lower alkyl.

Another group of preferred compounds of formula I are those, wherein R² is the group —NR³R⁴, R³ is hydrogen and R⁴ is selected from the group consisting of

-   lower alkyl, C₃-C₇-alkenyl, C₃-C₇-alkinyl, -   C₃-C₇-cycloalkyl, C₃-C₇-cycloalkyl substituted by phenyl, -   lower C₃-C₇-cycloalkylalkyl, -   unsubstituted phenyl or phenyl mono- or disubstituted by lower     alkyl, lower alkoxy, halogen or lower halogenalkyl, and -   lower phenylalkyl wherein phenyl is unsubstituted or mono- or     disubstituted by lower alkyl, lower alkoxy, halogen or lower     halogenalkyl.

Those compounds, wherein R³ is hydrogen and R⁴ is lower phenylalkyl wherein phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, are especially preferred.

Furthermore, compounds of formula I of the present invention are preferred, wherein m is 1 and R² is unsubstituted phenyl or phenyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl.

A preferred group of compounds of formula I are those, wherein X is SO₂. These are the compounds having the formula

wherein R¹, R² and m are as defined hereinbefore.

Furthermore, compounds of formula I are preferred, wherein X is C(O). These are compounds having the formula

wherein R¹, R² and m are as defined hereinbefore.

Within this group, those compounds are especially preferred wherein X is C(O) and R² is —NR³R⁴, thus meaning compounds of the formula

wherein R¹, R³, R⁴ and m are as defined hereinbefore.

Examples of preferred compounds of formula I are the following:

-   1-[6-(4-ethylpiperazin-1-yl)-pyridin-3-yl]-3-propyl-urea, -   1-cyclohexyl-3-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-benzyl-3-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-3-p-tolyl-urea, -   1-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-3-((1R,2S)-2-phenyl-cyclopropyl)-urea, -   1-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-3-(3-methoxy-phenyl)-urea, -   1-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-3-(4-fluoro-phenyl)-urea, -   1-cyclohexyl-3-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-benzyl-3-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-3-(4-methyl-benzyl)-urea, -   1-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-3-((1R,2S)-2-phenyl-cyclopropyl)-urea, -   1-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-3-(4-fluoro-phenyl)-urea, -   1-cyclohexyl-3-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-3-phenyl-urea, -   1-benzyl-3-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-3-o-tolyl-urea, -   1-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-3-m-tolyl-urea, -   1-(2-chloro-phenyl)-3-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-3-(4-methyl-benzyl)-urea, -   1-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-3-((1R,2S)-2-phenyl-cyclopropyl)-urea, -   1-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-3-(3-methoxy-phenyl)-urea, -   1-(4-fluoro-phenyl)-3-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-3-propyl-urea, -   1-cyclohexyl-3-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-benzyl-3-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-3-m-tolyl-urea, -   1-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-3-p-tolyl-urea, -   1-(2-chloro-phenyl)-3-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-3-(4-methyl-benzyl)-urea, -   1-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-3-((1R,2S)-2-phenyl-cyclopropyl)-urea, -   1-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-3-(3-methoxy-phenyl)-urea, -   1-(4-fluoro-phenyl)-3-[6-(4-isobutyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-dimethylaminosulfonamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-dimethylaminosulfonamide, -   N-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-dimethylaminosulfonamide, -   cyclohexanecarboxylic acid     [6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-2-phenyl-acetamide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-2-(4-fluoro-phenyl)-acetamide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-2-(3-methoxy-phenyl)-acetamide, -   2-(3,4-dimethoxy-phenyl)-N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-acetamide, -   [6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-carbamic acid     2-methoxy-ethyl ester, -   [6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-carbamic acid isobutyl     ester, -   cyclopropanecarboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-butyramide, -   cyclobutanecarboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   cyclopentanecarboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-2-ethyl-butyramide, -   cyclohexanecarboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   2-chloro-N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-nicotinamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-2-phenyl-acetamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-2-(4-fluoro-phenyl)-acetamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-2-(3-methoxy-phenyl)-acetamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-2-(3,4-dimethoxy-phenyl)-acetamide, -   [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-carbamic acid ethyl     ester, -   [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-carbamic acid     2-methoxy-ethyl ester, -   [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-carbamic acid     isobutyl ester, -   cyclohexanecarboxylic acid     [6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   2-(3,4-dimethoxy-phenyl)-N-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-acetamide, -   [6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-carbamic acid ethyl     ester, -   [6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-carbamic acid isobutyl     ester, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-butyramide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-methoxy-benzamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-phenyl-acetamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-(4-fluoro-phenyl)-acetamide, -   ethanesulfonic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-amide, -   propane-1-sulfonic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-amide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-dimethylaminosulfonamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-benzenesulfonamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-C-phenyl-methanesulfonamide, -   C-(4-chloro-phenyl)-N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-methanesulfonamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-fluoro-benzenesulfonamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-fluoro-benzenesulfonamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-4-fluoro-benzenesulfonamide, -   2-chloro-N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-benzenesulfonamide, -   4-chloro-N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-benzenesulfonamide, -   1-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-(4-fluoro-benzyl)-urea, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-methoxy-benzamide, -   N-[6-(4-Ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-phenyl-acetamide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-(4-fluoro-phenyl)-acetamide, -   ethanesulfonic acid     [6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-amide, -   propane-1-sulfonic acid     [6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-amide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-dimethylaminosulfonamide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-benzenesulfonamide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-C-phenyl-methanesulfonamide, -   C-(4-chloro-phenyl)-N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-methanesulfonamide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-fluoro-benzenesulfonamide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-fluoro-benzenesulfonamide, -   N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-4-fluoro-benzenesulfonamide, -   2-chloro-N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-benzenesulfonamide, -   4-chloro-N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-benzenesulfonamide, -   4-methyl-piperidine-1-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   2,6-dimethyl-piperidine-1-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   4-trifluoromethyl-piperidine-1-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   1-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylcarbamoyl]-piperidine-4-carboxylic     acid ethyl ester, -   octahydro-quinoline-1-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   octahydro-isoquinoline-2-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   2-trifluoromethyl-pyrrolidine-1-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   2-isopropyl-pyrrolidine-1-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   1,3-dihydro-isoindole-2-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   3-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-1-isopropyl-1-(2-methoxy-ethyl)-urea, -   azepane-1-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   3-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-1-ethyl-1-phenyl-urea, -   3-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-1-(4-methoxy-phenyl)-1-methyl-urea, -   3,4-dihydro-2H-quinoline-1-carboxylic acid     [6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-amide, -   3,4-dihydro-2H-quinoline-1-carboxylic acid     [6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-amide,     and pharmaceutically acceptable salts thereof.

Particularly preferred compounds of formula I of the present invention are the following:

-   1-benzyl-3-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-benzyl-3-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   1-[6-(4-byclopentyl-piperazin-1-yl)-pyridin-3-yl]-3-(4-methyl-benzyl)-urea, -   1-benzyl-3-[6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-urea, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-dimethylaminosulfonamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-2-(3,4-dimethoxy-phenyl)-acetamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-methoxy-benzamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-phenyl-acetamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-dimethylaminosulfonamide, -   N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-C-phenyl-methanesulfonamide, -   C-(4-chloro-phenyl)-N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-methanesulfonamide, -   2,6-dimethyl-piperidine-1-carboxylic acid     [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide,     and pharmaceutically acceptable salts thereof.

Furthermore, the pharmaceutically acceptable salts of the compounds of formula I and the pharmaceutically acceptable esters of the compounds of formula I individually constitute preferred embodiments of the present invention.

Compounds of formula I may form acid addition salts with acids, such as conventional pharmaceutically acceptable acids, for example hydrochloride, hydrobromide, phosphate, acetate, fumarate, maleate, salicylate, sulphate, pyruvate, citrate, lactate, mandelate, tartrate, and methanesulphonate. Preferred are the hydrochloride salts. Also solvates and hydrates of compounds of formula I and their salts form part of the present invention.

Furthermore, the N-atom of the pyridine ring can be present as an N-oxide group. Such N-oxides of compounds of formula I also form part of the present invention.

Compounds of formula I can have one or more asymmetric carbon atoms and can exist in the form of optically pure enantiomers, mixtures of enantiomers such as, for example, racemates, optically pure diastereoisomers, mixtures of diastereoisomers, diastereoisomeric racemates or mixtures of diastereoisomeric racemates. The optically active forms can be obtained for example by resolution of the racemates, by asymmetric synthesis or asymmetric chromatography (chromatography with a chiral adsorbens or eluant). The invention embraces all of these forms. It will be appreciated, that the compounds of general formula I in this invention may be derivatized at functional groups to provide derivatives which are capable of conversion back to the parent compound in vivo. Physiologically acceptable and metabolically labile derivatives, which are capable of producing the parent compounds of general formula I in vivo are also within the scope of this invention.

A further aspect of the present invention is the process for the manufacture of compounds of formula I as defined above, which process comprises

-   a) reacting a compound of the formula II

wherein R¹ and m are as defined herein before,

-   with a sulfonylchloride or sulfamoylchloride of the formula III     R²—SO₂—Cl  III     wherein R² is as defined herein before, -   to obtain a compound of the formula I-B

wherein R¹, R² and m are as defined herein before, or

-   b) reacting a compound of the formula II

wherein R¹ and m are as defined herein before,

-   with a chloride of the formula IV     R²—C(O)Cl  IV     wherein R² is as defined herein before, -   to obtain a compound of the formula I-A

wherein R¹, R² and m are as defined herein before, or

-   c) reacting a compound of the formula II

wherein R¹ and m are as defined herein before,

-   with an isocyanate of the formula V     R⁴—N═C═O  V     wherein R⁴ is as defined herein before, -   to obtain a compound of the formula I-C

wherein R³ is hydrogen and R¹, R⁴ and m are as defined herein before,

-   and if desired, converting the compound of formula I-A, I-B or I-C     into a pharmaceutically acceptable salt.

In more detail, the compounds of formula I can be manufactured by the methods given below, by the methods given in the examples or by analogous methods. Appropriate reaction conditions for the individual reaction steps are known to a person skilled in the art. Starting materials are either commercially available or can be prepared by methods analogous to the methods given below, by methods described in references cited in the text or in the examples, or by methods known in the art.

The preparation of compounds of formula I of the present invention may be carried out in sequential or convergent synthetic routes. Syntheses of the invention are shown in the following scheme. The skills required for carrying out the reaction and purification of the resulting products are known to those in the art. The substituents and indices used in the following description of the processes have the significance given herein before unless indicated to the contrary.

Compounds of general formula I can be prepared according to scheme 1 as follows:

a) The coupling of chloro substituted pyridine derivatives with piperazines is widely described in literature and the procedures are known to those in the art (For reaction conditions described in literature affecting such reactions see for example: Comprehensive Organic Transformations: A Guide to Functional Group Preparations, 2nd Edition, Richard C. Larock. John Wiley & Sons, New York, N.Y. 1999). 2-Chloro-5-cyanopyridine (VI) or 2-chloro-5-nitropyridine (IX) can conveniently be transformed to the respective pyridine derivative VIII or X through reaction with a piperazine derivative VII (either commercially available or accessible by methods described in references or by methods known in the art; as appropriate). The reaction can be carried out in the presence or the absence of a solvent and in the presence or the absence of a base. We find it convenient to carry out the reaction in a solvent like water and/or dimethylformamide (DMF) and in the presence of a base like diisopropyl-ethylamine (DIPEA). There is no particular restriction on the nature of the solvent to be employed, provided that it has no adverse effect on the reaction or the reagents involved and that it can dissolve the reagents, at least to some extent. Examples for suitable solvents include DMF, dichloromethane (DCM), dioxane, tetrahydrofurane (THF), and the like. There is no particular restriction on the nature of the base used in this stage, and any base commonly used in this type of reaction may equally be employed here. Examples of such bases include triethylamine and diisopropylethylamine, and the like. The reaction can take place over a wide range of temperatures, and the precise reaction temperature is not critical to the invention. We find it convenient to carry out the reaction with heating from ambient temperature to reflux. The time required for the reaction may also vary widely, depending on many factors, notably the reaction temperature and the nature of the reagents. A period of from 0.5 h to several days will usually suffice to yield pyridine derivatives VIII or X.

However, in the cases where the desired piperazine derivative is not easily accessible, an alternative route can be pursued leading to the pyridine derivatives VIII or X. Piperazine (VII; R¹═H) is reacted with 2-chloro-5-cyanopyridine (VI) or 2-chloro-5-nitropyridine (IX) to access the respective pyridine derivative VIII or X (R¹═H). The reaction can be carried out in the presence or the absence of a solvent and in the presence or the absence of a base. We find it convenient to carry out the reaction in a solvent like water and/or dimethylformamide (DMF) and in the presence of a base like triethylamine. There is no particular restriction on the nature of the solvent to be employed, provided that it has no adverse effect on the reaction or the reagents involved and that it can dissolve the reagents, at least to some extent. Examples for suitable solvents include: DMF, dichloromethane (DCM), dioxane, THF, and the like. There is no particular restriction on the nature of the base used in this stage, and any base commonly used in this type of reaction may equally be employed here. Examples of such bases include triethylamine and diisopropylethylamine, and the like. The reaction can take place over a wide range of temperatures, and the precise reaction temperature is not critical to the invention. We find it convenient to carry out the reaction with heating from ambient temperature to reflux. The time required for the reaction may also vary widely, depending on many factors, notably the reaction temperature and the nature of the reagents. However, a period of from 0.5 h to several days will usually suffice to yield pyridine derivatives VIII or X. Subsequently, to access the pyridine derivatives VIII or X (R¹≠H) the intermediate is subjected to reductive amination reaction conditions with suitable aldehydes or alkylating reaction conditions with suitable alkylating reagents. The reaction conditions for either reaction are widely described in literature and the procedures are known to those in the art (For reaction conditions described in literature affecting such reactions see for example: Comprehensive Organic Transformations: A Guide to Functional Group Preparations, 2nd Edition, Richard C. Larock. John Wiley & Sons, New York, N.Y. 1999).

b) The reduction of the cyano or nitro functionality in VIII or X respectively can be achieved under various reducing reaction conditions to access the aminomethyl pyridine derivatives II-A (compounds of formula II wherein m is 1) or the aminopyridine derivatives II-B (compounds of formula II wherein m is 0). The reaction conditions for either reaction are widely described in literature and the procedures are known to those in the art (For reaction conditions described in literature affecting such reactions see for example: Comprehensive Organic Transformations: A Guide to Functional Group Preparations, 2nd Edition, Richard C. Larock. John Wiley & Sons, New York, N.Y. 1999). We find it convenient to hydrogenate VIII or X over Raney Nickel or palladium/charcoal (Pd/C) in a solvent and in the presence or absence of an acid. We find it convenient to carry out the reaction in a solvent like methanol or ethyl acetate. There is no particular restriction on the nature of the solvent to be employed, provided that it has no adverse effect on the reaction or the reagents involved and that it can dissolve the reagents, at least to some extent. Examples for suitable solvents include: methanol, ethanol, ethyl acetate, and the like. There is no particular restriction on the nature of the acid used in this stage, and any base commonly used in this type of reaction may equally be employed here. Examples of such acids include acetic acid or HCl, and the like. The reduction can be achieved through hydrogen, however any other reducing agents employed in such reaction might equally be employed here. Neither the precise hydrogen pressure nor the precise reaction temperature are critical to the invention The reaction can take place over a wide range of temperatures, and a wide range of hydrogen pressure. We find it convenient to carry out the reaction with heating from ambient temperature to reflux. The time required for the reaction may also vary widely, depending on many factors, notably the reaction temperature and the nature of the reagents. However, a period of from 0.5 h to several days will usually suffice to yield pyridine derivatives II-A (m is 1).

c) Sulfonamides, amides, carbamates and ureas can be prepared from suitable starting materials according to methods known in the art. The conversion of the amino-moiety in II-A or II-B to access sulfonamides, amides, carbamates and ureas can be affected by methods described in literature. For example the conversion of the amine derivatives II to access compounds of the general formula I is affected by reaction of II with suitable with sulfonyl chlorides or sulfamoyl chlorides (compounds of formula III) or acid chlorides, chloroformates, or carbonate esters (compounds of formula IV as defined herein before) or with isocyanates (compounds of formula V), respectively, in a solvent like dichloromethane and in the presence or the absence of a base. The compounds of formula III, IV or V are known or can be prepared by known methods. There is no particular restriction on the nature of the solvent to be employed, provided that it has no adverse effect on the reaction or the reagents involved and that it can dissolve the reagents, at least to some extent. Examples for suitable solvents include: chloroform, or dioxane, THF, and the like. There is no particular restriction on the nature of the base used in this stage, and any base commonly used in this type of reaction may equally be employed here. Examples of such bases include triethylamine and diisopropylethyl-amine, and the like. The reaction can take place over a wide range of temperatures, and the precise reaction temperature is not critical to the invention. We find it convenient to carry out the reaction with heating from ambient temperature to reflux. The time required for the reaction may also vary widely, depending on many factors, notably the reaction temperature and the nature of the reagents. However, a period of from 0.5 h to several days will usually suffice to yield pyridine derivatives I. For reaction conditions described in literature affecting such reactions see for example: Comprehensive Organic Transformations: A Guide to Functional Group Preparations, 2nd Edition, Richard C. Larock. John Wiley & Sons, New York, N.Y. 1999.

As described above, the compounds of formula I of the present invention can be used as medicaments for the treatment and/or prevention of diseases which are associated with the modulation of H3 receptors. Examples of such diseases are obesity, metabolic syndrome (syndrome X), neurological diseases including Alzheimer's disease, dementia, age-related memory dysfunction, mild cognitive impairment, cognitive deficit, attention deficit hyperactivity disorder, epilepsy, neuropathic pain, inflammatory pain, migraine, Parkinson's disease, multiple sclerosis, stroke, dizziness, schizophrenia, depression, addiction, motion sickness and sleep disorders including narcolepsy, and other diseases including asthma, allergy, allergy-induced airway responses, congestion, chronic obstructive pulmonary disease and gastro-intestinal disorders. The use as medicament for the treatment and/or prevention of obesity is preferred.

The invention therefore also relates to pharmaceutical compositions comprising a compound as defined above and a pharmaceutically acceptable carrier and/or adjuvant.

Further, the invention relates to compounds as defined above for use as therapeutically active substances, particularly as therapeutic active substances for the treatment and/or prevention of diseases which are associated with the modulation of H3 receptors. Examples of such diseases are obesity, metabolic syndrome (syndrome X), neurological diseases including Alzheimer's disease, dementia, age-related memory dysfunction, mild cognitive impairment, cognitive deficit, attention deficit hyperactivity disorder, epilepsy, neuropathic pain, inflammatory pain, migraine, Parkinson's disease, multiple sclerosis, stroke, dizziness, schizophrenia, depression, addiction, motion sickness and sleep disorders including narcolepsy, and other diseases including asthma, allergy, allergy-induced airway responses, congestion, chronic obstructive pulmonary disease and gastro-intestinal disorders.

In another embodiment, the invention relates to a method for the treatment and/or prevention of diseases which are associated with the modulation of H3 receptors. Examples of such diseases are obesity, metabolic syndrome (syndrome X), neurological diseases including Alzheimer's disease, dementia, age-related memory dysfunction, mild cognitive impairment, cognitive deficit, attention deficit hyperactivity disorder, epilepsy, neuropathic pain, inflammatory pain, migraine, Parkinson's disease, multiple sclerosis, stroke, dizziness, schizophrenia, depression, addiction, motion sickness and sleep disorders including narcolepsy, and other diseases including asthma, allergy, allergy-induced airway responses, congestion, chronic obstructive pulmonary disease and gastro-intestinal disorders. A method for the treatment and/or prevention of obesity is preferred.

The invention further relates to the use of compounds of formula I as defined above for the treatment and/or prevention of diseases which are associated with the modulation of H3 receptors. Examples of such diseases are obesity, metabolic syndrome (syndrome X), neurological diseases including Alzheimer's disease, dementia, age-related memory dysfunction, mild cognitive impairment, cognitive deficit, attention deficit hyperactivity disorder, epilepsy, neuropathic pain, inflammatory pain, migraine, Parkinson's disease, multiple sclerosis, stroke, dizziness, schizophrenia, depression, addiction, motion sickness and sleep disorders including narcolepsy, and other diseases including asthma, allergy, allergy-induced airway responses, congestion, chronic obstructive pulmonary disease and gastro-intestinal disorders. The use of compounds of formula I as defined above for the treatment and/or prevention of obesity is preferred.

In addition, the invention relates to the use of compounds of formula I as defined above for the preparation of medicaments for the treatment and/or prevention of diseases which are associated with the modulation of H3 receptors. Examples of such diseases are obesity, metabolic syndrome (syndrome X), neurological diseases including Alzheimer's disease, dementia, age-related memory dysfunction, mild cognitive impairment, cognitive deficit, attention deficit hyperactivity disorder, epilepsy, neuropathic pain, inflammatory pain, migraine, Parkinson's disease, multiple sclerosis, stroke, dizziness, schizophrenia, depression, addiction, motion sickness and sleep disorders including narcolepsy, and other diseases including asthma, allergy, allergy-induced airway responses, congestion, chronic obstructive pulmonary disease and gastro-intestinal disorders. The use of compounds of formula I as defined above for the preparation of medicaments for the treatment and/or prevention of obesity is preferred.

The compounds of formula I and their pharmaceutically acceptable salts possess valuable pharmacological properties. Specifically, it has been found that the compounds of the present invention are good histamine 3 receptor (H3R) antagonists and/or inverse agonists.

The compounds of formula (I) and their pharmaceutically acceptable salts and esters can be used as medicaments, e.g. in the form of pharmaceutical preparations for enteral, parenteral or topical administration. They can be administered, for example, perorally, e.g. in the form of tablets, coated tablets, dragées, hard and soft gelatine capsules, solutions, emulsions or suspensions, rectally, e.g. in the form of suppositories, parenterally, e.g. in the form of injection solutions or infusion solutions, or topically, e.g. in the form of ointments, creams or oils.

The production of the pharmaceutical preparations can be effected in a manner which will be familiar to any person skilled in the art by bringing the described compounds of formula (I) and their pharmaceutically acceptable, into a galenical administration form together with suitable, non-toxic, inert, therapeutically compatible solid or liquid carrier materials and, if desired, usual pharmaceutical adjuvants.

Suitable carrier materials are not only inorganic carrier materials, but also organic carrier materials. Thus, for example, lactose, corn starch or derivatives thereof, talc, stearic acid or its salts can be used as carrier materials for tablets, coated tablets, dragées and hard gelatine capsules. Suitable carrier materials for soft gelatine capsules are, for example, vegetable oils, waxes, fats and semi-solid and liquid polyols (depending on the nature of the active ingredient no carriers are, however, required in the case of soft gelatine capsules). Suitable carrier materials for the production of solutions and syrups are, for example, water, polyols, sucrose, invert sugar and the like. Suitable carrier materials for injection solutions are, for example, water, alcohols, polyols, glycerol and vegetable oils. Suitable carrier materials for suppositories are, for example, natural or hardened oils, waxes, fats and semi-liquid or liquid polyols. Suitable carrier materials for topical preparations are glycerides, semi-synthetic and synthetic glycerides, hydrogenated oils, liquid waxes, liquid paraffins, liquid fatty alcohols, sterols, polyethylene glycols and cellulose derivatives.

Usual stabilizers, preservatives, wetting and emulsifying agents, consistency-improving agents, flavor-improving agents, salts for varying the osmotic pressure, buffer substances, solubilizers, colorants and masking agents and antioxidants come into consideration as pharmaceutical adjuvants.

The dosage of the compounds of formula (I) can vary within wide limits depending on the disease to be controlled, the age and the individual condition of the patient and the mode of administration, and will, of course, be fitted to the individual requirements in each particular case. For adult patients a daily dosage of about 1 mg to about 1000 mg, especially about 1 mg to about 100 mg, comes into consideration. Depending on the dosage it is convenient to administer the daily dosage in several dosage units.

The pharmaceutical preparations conveniently contain about 0.1-500 mg, preferably 0.5-100 mg, of a compound of formula (I).

The following examples serve to illustrate the present invention in more detail. They are, however, not intended to limit its scope in any manner.

EXAMPLES Intermediate 1 1-Ethyl-4-(5-nitro-pyridin-2-yl)-piperazine

A mixture of 2 g (13 mmol) 2-chloro-5-nitro-pyridine and 0.76 g (6 mmol) N,N-diisopropylethylamine in 21 ml water and 4 ml DMF was heated to 80° C. During 2 min 1.73 g (15 mmol) N-ethylpiperazine was added and the mixture was kept for an additional hour at 80° C. The yellow precipitate was filtered off and washed three times with 4 ml water and dried for 16 h under vacuum to yield 2.48 g (83%) of the title compound as yellow crystals. (m/e): 237.1 (MH⁺; 100%).

Intermediate 2 6-(4-Ethyl-piperazin-1-yl)-pyridin-3-ylamine

A mixture of 2.47 g (10 mmol) 1-ethyl-4-(5-nitro-pyridin-2-yl)-piperazine and 0.247 g Pd/C (10%) in 25 ml methanol was treated with 1 bar hydrogen at room temperature for 2 h. After filtration the mixture was evaporated to dryness to yield 2.12 g (98%) of the title compound as colorless solid. (m/e): 207.3 (MH⁺; 100%).

Intermediate 3 1-Isopropyl-4-(5-nitro-pyridin-2-yl)-piperazine

According to the procedure described for the synthesis of intermediate 1 1-isopropyl-4-(5-nitro-pyridin-2-yl)-piperazine was synthesized from 2-chloro-5-nitro-pyridine and N-isopropylpiperazine to yield 97% of the title compound as yellow crystals. (m/e): 251.1 (MH⁺; 100%).

Intermediate 4 6-(4-Isopropyl-piperazin-1-yl)-pyridin-3-ylamine

According to the procedure described for the synthesis of intermediate 2 6-(4-isopropyl-piperazin-1-yl)-pyridin-3-ylamine was synthesized from 1-isopropyl-4-(5-nitro-pyridin-2-yl)-piperazine through hydrogenation to yield the title compound which was used without further purification in the following step. (m/e): 221.1 (MH⁺; 100%).

Intermediate 5 1-Cyclopentyl-4-(5-nitro-pyridin-2-yl)-piperazine

According to the procedure described for the synthesis of intermediate 1 1-cyclopentyl-4-(5-nitro-pyridin-2-yl)-piperazine was synthesized from 2-chloro-5-nitro-pyridine and N-cyclopentylpiperazine to yield 87% of the title compound as yellow crystals. (m/e): 277.1 (MH⁺; 100%).

Intermediate 6 6-(4-Cyclopentyl-piperazin-1-yl)-pyridin-3-ylamine

According to the procedure described for the synthesis of intermediate 2-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylamine was synthesized from 1-cyclopentyl-4-(5-nitro-pyridin-2-yl)-piperazine through hydrogenation to yield 98% of the title compound as colorless crystals. (m/e): 247.1 (MH⁺; 100%).

Intermediate 7 1-Isobutyl-4-(5-nitro-pyridin-2-yl)-piperazine

A mixture of 7 g (34 mmol) 1-(5-nitro-pyridin-2-yl)-piperazine (commercially available), 3.15 g (44 mmol) isobutytraldehyde, 10.7 g (50 mmol) sodium trisacetoxyborohydride in 140 ml THF and 3 ml acetic acid was stirred at room temperature for 16 h. After addition of 50 ml water, THF was removed under vacuum. The residue was taken up in 300 ml water and 400 ml ethyl acetate and made alkaline by addition of 2M aq. Na₂CO₃ solution. The mixture was afterwards extracted two times with 300 ml ethyl acetate each. The combined organic phases were washed two times with 200 ml water each, dried with MgSO₄ and evaporated to dryness. The residue was used without further purification in the synthesis of intermediate 9. (m/e): 265.0 (MH⁺; 100%).

Intermediate 8 6-(4-Isobutyl-piperazin-1-yl)-pyridin-3-ylamine

A mixture of 2.48 g 1-isobutyl-4-(5-nitro-pyridin-2-yl)-piperazine (intermediate 7) and 0.8 g Pd/C (10%) in 30 ml methanol was treated with 1 bar hydrogen at room temperature for 2 h. After filtration the mixture was evaporated to dryness to yield 2.09 g (95%) of the title compound as colorless solid. (m/e): 235.0 (MH⁺; 100%).

Example 1 1-[6-(4-Ethyl-piperazin-1-yl)-pyridin-3-yl]-3-propyl-urea

A mixture of 20 mg (0.1 mmol) 6-(4-isobutyl-piperazin-1-yl)-pyridin-3-ylamine, 15 mg (0.15 mmol) triethylamine and 9.4 mg (0.11 mmol) 1-isocyanato-propane in 1 ml DCM was stirred at room temperature for 16 h. After evaporation the residue was taken up in 1 ml methanol/acetonitrile 1/1 and subjected to preparative HPLC purification on reversed phase eluting with a gradient of acetonitrile/water (0.05% triethylamine). The combined product fractions were evaporated to dryness to yield 15.5 mg (53%) of the title compound. (m/e): 292.3 (MH⁺; 100%).

According to the procedure described for the synthesis of Example 1 further pyridine derivatives have been synthesized from the intermediates 2, 4, 6 and 8, respectively, and commercially available reagents listed in table 1. The examples are compiled in table 1 and comprise Examples No 2 to 60.

TABLE 1 MH+ No MW Name Starting materials found 2 331.46 1-cyclohexyl-3-[6-(4-ethyl- 6-(4-ethyl-piperazin-1-yl)-pyridin- 332 piperazin-1-yl)-pyridin-3- 3-ylamine (intermediate 2) and yl]-urea 1-isocyanato-cyclohexane 3 339.44 1-benzyl-3-[6-(4-ethyl- 6-(4-ethyl-piperazin-1-yl)-pyridin- 340.3 piperazin-1-yl)-pyridin-3- 3-ylamine (intermediate 2) and yl]-urea isocyanatomethyl-benzene 4 339.44 1-[6-(4-ethyl-piperazin-1- 6-(4-ethyl-piperazin-1-yl)-pyridin- 340.3 yl)-pyridin-3-yl]-3-p-tolyl- 3-ylamine (intermediate 2) and urea 1-isocyanato-4-methyl-benzene 5 365.48 1-[6-(4-ethyl-piperazin-1- 6-(4-ethyl-piperazin-1-yl)-pyridin- 366.3 yl)-pyridin-3-yl]-3-((1R,2S)- 3-ylamine (intermediate 2) and 2-phenyl-cyclopropyl)-urea ((1R,2S)-2-isocyanato-cyclopropyl)- benzene 6 355.44 1-[6-(4-ethyl-piperazin-1- 6-(4-ethyl-piperazin-1-yl)-pyridin- 355.8 yl)-pyridin-3-yl]-3-(3- 3-ylamine (intermediate 2) and methoxy-phenyl)-urea 1-isocyanato-3-methoxy-benzene 7 343.41 1-[6-(4-ethyl-piperazin-1- 6-(4-ethyl-piperazin-1-yl)-pyridin- 344.2 yl)-pyridin-3-yl]-3-(4- 3-ylamine (intermediate 2) and fluoro-phenyl)-urea 1-isocyanato-4-fluoro-benzene 8 371.53 1-cyclohexyl-3-[6-(4- 6-(4-Cyclopentyl-piperazin-1-yl)- 372.3 cyclopentyl-piperazin-1-yl)- pyridin-3-ylamine (intermediate 6) pyridin-3-yl]-urea and isocyanato-cyclohexane 9 379.51 1-benzyl-3-[6-(4- 6-(4-cyclopentyl-piperazin-1-yl)- 380.4 cyclopentyl-piperazin-1-yl)- pyridin-3-ylamine (intermediate 6) pyridin-3-yl]-urea and isocyanato-methylbenzene 10 393.53 1-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- 394.2 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]-3-(4-methyl-benzyl)-urea and 1-isocyanatomethyl-4- methylbenzene 11 405.55 1-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- 406.5 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]-3-(( 1R,2S)-2-phenyl- and cyclopropyl)-urea ((1R,2S)-2-isocyanato-cyclopropyl)- benzene 12 383.47 1-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- 383.9 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]-3-(4-fluoro-phenyl)-urea and 1-isocyanato-4-fluorobenzene 13 345.49 1-cyclohexyl-3-[6-(4- 6-(4-isopropyl-piperazin-1-yl)- 345.3 isopropyl-piperazin-1-yl)- pyridin-3-ylamine (intermediate 4) pyridin-3-yl]-urea and isocyanato-cyclohexane 14 339.44 1-[6-(4-isopropyl-piperazin- 6-(4-isopropyl-piperazin-1-yl)- 340.2 1-yl)-pyridin-3-yl]-3-phenyl- pyridin-3-ylamine (intermediate 4) urea and isocyanato-benzene 15 353.47 1-benzyl-3-[6-(4-isopropyl- 6-(4-isopropyl-piperazin-1-yl)- 354.3 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 4) yl]-urea and isocyanatomethyl-benzene 16 353.47 1-[6-(4-isopropyl-piperazin- 6-(4-isopropyl-piperazin-1-yl)- 353.9 1-yl)-pyridin-3-yl]-3-o-tolyl- pyridin-3-ylamine (intermediate 4) urea and 1-isocyanato-2-methyl-benzene 17 353.47 1-[6-(4-isopropyl-piperazin- 6-(4-isopropyl-piperazin-1-yl)- 354.3 1-yl)-pyridin-3-yl]-3-m- pyridin-3-ylamine (intermediate 4) tolyl-urea and 1-isocyanato-3-methyl-benzene 18 373.89 1-(2-chloro-phenyl)-3-[6-(4- 6-(4-isopropyl-piperazin-1-yl)- 374.2 isopropyl-piperazin-1-yl)- pyridin-3-ylamine (intermediate 4) pyridin-3-yl]-urea and 1-isocyanato-2-chloro-benzene 19 367.5 1-[6-(4-isopropyl-piperazin- 6-(4-isopropyl-piperazin-1-yl)- 368.2 1-yl)-pyridin-3-yl]-3-(4- pyridin-3-ylamine (intermediate 4) methyl-benzyl)-urea and isocyanatomethyl-4-methyl-benzene 20 379.51 1-[6-(4-isopropyl-piperazin- 6-(4-isopropyl-piperazin-1-yl) 379.9 1-yl)-pyridin-3-yl]-3- pyridin-3-ylamine (intermediate 4) ((1R,2S)-2-phenyl- and cyclopropyl)-urea ((1R,2S)-2-isocyanato-cyclopropyl)- benzene 21 369.47 1-[6-(4-isopropyl-piperazin- 6-(4-isopropyl-piperazin-1-yl)- 370.3 1-yl)-pyridin-3-yl]-3-(3- pyridin-3-ylamine (intermediate 4) methoxy-phenyl)-urea and 1-isocyanato-3-methoxy-benzene 22 357.43 1-(4-fluoro-phenyl)-3-[6-(4- 6-(4-isopropyl-piperazin-1-yl)- 358.2 isopropyl-piperazin-1-yl)- pyridin-3-ylamine (intermediate 4) pyridin-3-yl]-urea and 1-isocyanato-4-fluoro-benzene 23 319.45 1-[6-(4-isobutyl-piperazin-1- 6-(4-isobutyl-piperazin-1-yl)- 327.3 yl)-pyridin-3-yl]-3-propyl- pyridin-3-ylamine (intermediate 8) urea and 1-isocyanato-propane 24 359.52 1-cyclohexyl-3-[6-(4- 6-(4-isobutyl-piperazin-1-yl)- 359.9 isobutyl-piperazin-1-yl)- pyridin-3-ylamine (intermediate 8) pyridin-3-yl]-urea and isocyanato-cyclohexane 25 367.5 1-benzyl-3-[6-(4-isobutyl- 6-(4-isobutyl-piperazin-1-yl)- 368.2 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 8) yl]-urea and isocyanatomethyl-benzene 26 367.5 1-[6-(4-isobutyl-piperazin-1- 6-(4-isobutyl-piperazin-1-yl)- 368.2 yl)-pyridin-3-yl]-3-m-tolyl- pyridin-3-ylamine (intermediate 8) urea and 1-isocyanato-3-methyl-benzene 27 367.5 1-[6-(4-isobutyl-piperazin-1- 6-(4-isobutyl-piperazin-1-yl)- 368.2 yl)-pyridin-3-yl]-3-p-tolyl- pyridin-3-ylamine (intermediate 8) urea and 1-isocyanato-4-methyl-benzene 28 387.91 1-(2-chloro-phenyl)-3-[6-(4- 6-(4-isobutyl-piperazin-1-yl)- 387.9 isobutyl-piperazin-1-yl)- pyridin-3-ylamine (intermediate 8) pyridin-3-yl]-urea and 1-isocyanato-2-chloro-benzene 29 381.52 1-[6-(4-isobutyl-piperazin-1- 6-(4-isobutyl-piperazin-1-yl)- 382 yl)-pyridin-3-yl]-3-(4- pyridin-3-ylamine (intermediate 8) methyl-benzyl)-urea and isocyanatomethyl-4-methyl- benzene 30 393.53 1-[6-(4-isobutyl-piperazin-1- 6-(4-isobutyl-piperazin-1-yl)- 393.9 yl)-pyridin-3-yl]-3-((1R,2S)- pyridin-3-ylamine (intermediate 8) 2-phenyl-cyclopropyl)-urea and ((1R,2S)-2-isocyanato-cyclopropyl)- benzene 31 383.5 1-[6-(4-isobutyl-piperazin-1- 6-(4-isobutyl-piperazin-1-yl)- 384.3 yl)-pyridin-3-yl]-3-(3- pyridin-3-ylamine (intermediate 8) methoxy-phenyl)-urea and 1-isocyanato-3-methoxy-benzene 32 371.46 1-(4-fluoro-phenyl)-3-[6-(4- 6-(4-isobutyl-piperazin-1-yl)- 371.4 isobutyl-piperazin-1-yl)- pyridin-3-ylamine (intermediate 8) pyridin-3-yl]-urea and 1-isocyanato-4-fluoro-benzene 33 313.42 N-[6-(4-ethyl-piperazin-1- 6-(4-ethyl-piperazin-1-yl)-pyridin- yl)-pyridin-3-yl]- 3-ylamine (intermediate 2) and diemethylaminosulfonamide dimethylaminosulfamoylchloride 34 353.49 N-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]- and diemethylaminosulfonamide dimethylaminosulfamoylchloride 35 327.45 N-[6-(4-isopropyl-piperazin- 6-(4-isopropyl-piperazin-1-yl)- 1-yl)-pyridin-3-yl]- pyridin-3-ylamine (intermediate 4) diemethylaminosulfonamide and dimethylaminosulfamoylchloride 36 316.45 cyclohexanecarboxylic acid 6-(4-ethyl-piperazin-1-yl)-pyridin- 317.3 [6-(4-ethyl-piperazin-1-yl)- 3-ylamine (intermediate 2) and pyridin-3-yl]-amide cyclohexanecarbonyl chloride 37 324.43 N-[6-(4-ethyl-piperazin-1- 6-(4-ethyl-piperazin-1-yl)-pyridin- 325.4 yl)-pyridin-3-yl]-2-phenyl- 3-ylamine (intermediate 2) and acetamide phenyl-acetyl chloride 38 342.42 N-[6-(4-ethyl-piperazin-1- 6-(4-ethyl-piperazin-1-yl)-pyridin- 343.2 yl)-pyridin-3-yl]-2-(4- 3-ylamine (intermediate 2) and fluoro-phenyl)-acetamide (4-fluoro-phenyl)-acetyl chloride 39 354.45 N-[6-(4-ethyl-piperazin-1- 6-(4-ethyl-piperazin-1-yl)-pyridin- 355.4 yl)-pyridin-3-yl]-2-(3- 3-ylamine (intermediate 2) and methoxy-phenyl)-acetamide (3-methoxy-phenyl)-acetyl chloride 40 384.48 2-(3,4-dimethoxy-phenyl)- 6-(4-ethyl-piperazin-1-yl)-pyridin- 385.3 N-[6-(4-ethyl-piperazin-1- 3-ylamine (intermediate 2) and yl)-pyridin-3-yl]-acetamide (3,4-dimethoxy-phenyl)-acetyl chloride 41 308.38 [6-(4-ethyl-piperazin-1-yl)- 6-(4-ethyl-piperazin-1-yl)-pyridin- 309.4 pyridin-3-yl]-carbamic acid 3-ylamine (intermediate 2) and 2-methoxy-ethyl ester 2-methoxy-ethanol carbonyl chloride 42 306.41 [6-(4-ethyl-piperazin-1-yl)- 6-(4-ethyl-piperazin-1-yl)-pyridin- 307.4 pyridin-3-yl]-carbamic acid 3-ylamine (intermediate 2) and isobutyl ester carbonic acid chloride monoisobutyl ester 43 314.43 cyclopropanecarboxylic acid 6-(4-cyclopentyl-piperazin-1-yl) 315.2 [6-(4-cyclopentyl-piperazin- pyridin-3-ylamine (intermediate 6) 1-yl)-pyridin-3-yl]-amide and cyclopropanecarbonyl chloride 44 316.45 N-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- 317.3 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]-butyramide and butyryl chloride 45 328.46 cyclobutanecarboxylic acid 6-(4-cyclopentyl-piperazin-1-yl)- 329.4 [6-(4-cyclopentyl-piperazin- pyridin-3-ylamine (intermediate 6) 1-yl)-pyridin-3-yl]-amide and cyclobutanecarbonyl chloride 46 342.49 cyclopentanecarboxylic acid 6-(4-cyclopentyl-piperazin-1-yl)- 343.4 [6-(4-cyclopentyl-piperazin- pyridin-3-ylamine (intermediate 6) 1-yl)-pyridin-3-yl]-amide and cyclopentanecarbonyl chloride 47 344.5 N-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- 345.3 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]-2-ethyl-butyramide and 2-ethyl-butyryl chloride 48 356.51 cyclohexanecarboxylic acid 6-(4-cyclopentyl-piperazin-1-yl)- 357.3 [6-(4-cyclopentyl-piperazin- pyridin-3-ylamine (intermediate 6) 1-yl)-pyridin-3-yl]-amide and cyclohexanecarbonyl chloride 49 385.9 2-chloro-N-[6-(4- 6-(4-cyclopentyl-piperazin-1-yl)- 386.3 cyclopentyl-piperazin-1-yl)- pyridin-3-ylamine (intermediate 6) pyridin-3-yl]-nicotinamide and 2-chloro-nicotinoyl chloride 50 364.49 N-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- 365.4 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]-2-phenyl-acetamide and phenyl-acetyl chloride 51 382.48 N-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- 383.3 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]-2-(4-fluoro-phenyl)- and acetamide (4-fluoro-phenyl)-acetyl chloride 52 394.52 N-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- 395.3 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]-2-(3-methoxy-phenyl)- and acetamide (3-methoxy-phenyl)-acetyl chloride 53 424.54 N-[6-(4-cyclopentyl- 6-(4-cyclopentyl-piperazin-1-yl)- 425.3 piperazin-1-yl)-pyridin-3- pyridin-3-ylamine (intermediate 6) yl]-2-(3,4-dimethoxy- and phenyl)-acetamide (3,4-dimethoxy-phenyl)-acetyl chloride 54 318.42 [6-(4-cyclopentyl-piperazin- 6-(4-cyclopentyl-piperazin-1-yl)- 319.3 1-yl)-pyridin-3-yl]-carbamic pyridin-3-ylamine (intermediate 6) acid ethyl ester and carbonic acid monoethyl ester 55 348.45 [6-(4-cyclopentyl-piperazin- 6-(4-cyclopentyl-piperazin-1-yl)- 349.4 1-yl)-pyridin-3-yl]-carbamic pyridin-3-ylamine (intermediate 6) acid 2-methoxy-ethyl ester and carbonic acid mono (2- methoxyethyl) ester 56 346.47 [6-(4-cyclopentyl-piperazin- 6-(4-cyclopentyl-piperazin-1-yl)- 347.3 1-yl)-pyridin-3-yl]-carbamic pyridin-3-ylamine (intermediate 6) acid isobutyl ester and carbonic acid monoisobutyl ester 57 330.48 cyclohexanecarboxylic acid 6-(4-isopropyl-piperazin-1-yl)- 331.3 [6-(4-isopropyl-piperazin-1- pyridin-3-ylamine (intermediate 4) yl)-pyridin-3-yl]-amide and cyclohexanecarbonyl chloride 58 398.51 2-(3,4-dimethoxy-phenyl)- 6-(4-isopropyl-piperazin-1-yl)- 399.2 N-[6-(4-isopropyl-piperazin- pyridin-3-ylamine (intermediate 4) 1-yl)-pyridin-3-yl]- and acetamide (3,4-dimethoxy-phenyl)-acetyl chloride 59 292.38 [6-(4-isopropyl-piperazin-1- 6-(4-isopropyl-piperazin-1-yl)- 293.3 yl)-pyridin-3-yl]-carbamic pyridin-3-ylamine (intermediate 4) acid ethyl ester and carbonic acid monoethyl ester 60 320.44 [6-(4-isopropyl-piperazin-1- 6-(4-isopropyl-piperazin-1-yl)- 321.3 yl)-pyridin-3-yl]-carbamic pyridin-3-ylamine (intermediate 4) acid isobutyl ester and carbonic acid monoisobutyl ester

Intermediate 9 6-(4-Ethyl-piperazin-1-yl)-nicotinonitrile

A mixture of 2 g (14 mmol) 6-chloronicotinonitrile (commercially available) and 0.88 g (7 mmol) N,N-diisopropylethylamine in 20 ml water and 4 ml DMF was heated to 80° C. During 2 min 1.98 g (17 mmol) N-ethylpiperazine was added and stirred at 80° C. for 1 h. 100 ml 1M aq. Na₂CO₃ solution was added and the mixture was extracted three times with 100 ml ethyl acetate each. The combined organic phases were washed twice with 100 ml brine each and dried with MgSO4. After evaporation the residue was purified with flash chromatography on Alox eluting with a gradient of ethyl acetate/heptan to yield 1.4 g (45%) of the title compound as slightly yellow crystals. (m/e): 21702 (MH⁺; 100%).

Intermediate 10 C-[6-(4-Ethyl-piperazin-1-yl)-pyridin-3-yl]-methylamine

A mixture of 2 g (8 mmol) 6-(4-ethyl-piperazin-1-yl)-nicotinonitrile, 1.3 g Raney Nickel (B113Z, Degussa) in 25 ml methanol, 15 ml ethyl acetate and 5 ml ammonia aq. (ca. 25%) was treated with 1 bar hydrogen at 30-35° C. for 4 h. The mixture was filtered and the residue washed three times with 20 ml ethyl acetate each and the combined organic phases evaporated to dryness to yield 1.83 g (97%) of the title compound as white crystals. (m/e): 261.1 (MH⁺; 100%).

Intermediate 11 6-(4-Cyclopentyl-piperazin-1-yl)-nicotinonitrile

A mixture of 2 g (14 mmol) 6-chloronicotinonitrile (commercially available) 2.45 g (16 mmol) N-cyclopentylpiperazine (commercially available) and 1.86 g (14 mmol) N,N-diisopropylethylamine in 5 ml water and 15 ml DMF was heated to 90° C. for 24 h. After addition of 250 ml 1M NaHCO3 aq. solution the mixture was extracted three times with 250 ml ethyl acetate each. The combined organic phases were washed twice with 150 ml brine each, dried and evaporated to dryness. Recrystallization from ethyl acetate yielded a first batch of 2.83 g of white crystals. An additional batch was yielded from the filtrate and in total 3.14 g (85%)n of the title compound was obtained as white crystals. (m/e): 257.1 (MH⁺; 100%).

Intermediate 12 C-[6-(4-Cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-methylamine

According to the procedure described for the synthesis of intermediate 10 C-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-methylamine was synthesized from 6-(4-cyclopentyl-piperazin-1-yl)-nicotinonitrile through hydrogenation over Raney Nickel. 1.99 g (98%) of the title compounds was obtained as white crystals. (m/e): 261.1 (MH⁺; 100%).

Example 61 N-[6-(4-Cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-butyramide

A mixture of 26 mg (0.1 mmol) C-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-methylamine, 20 mg (0.2 mmol) triethylamine and 12 mg (0.11 mmol) butyryl chloride in DCM was stirred at room temperature. After evaporation acetonitrile/DMF was added and the mixture was subjected to preparative HPLC purification on reversed phase eluting with a gradient of acetonitrile/water (0.05% triethylamine). The combined product fractions were evaporated to dryness to yield 20.3 mg (61%) of the title compound. (m/e): 331.3

According to the procedure described for the synthesis of example 73 further pyridine derivatives have been synthesized from C-[6-(4-Ethyl-piperazin-1-yl)-pyridin-3-yl]-methylamine and C-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-methylamine and the respective commercially available reagent mentioned in Table 2. The Examples are shown in table 2 and comprise Examples No 62 to 90.

TABLE 2 MH+ No MW Name Starting materials found 62 394.52 N-[6-(4-cyclopentyl- C-[6-(4-cyclopentyl-piperazin-1-yl)- 395.3 piperazin-1-yl)-pyridin-3- pyridin-3-yl]-methylamine (intermediate ylmethyl]-3-methoxy- 12) and benzamide 3-methoxy-benzoyl chloride 63 378.52 N-[6-(4-cyclopentyl- C-[6-(4-cyclopentyl-piperazin-1-yl)- 379.4 piperazin-1-yl)-pyridin-3- pyridin-3-yl]-methylamine (intermediate ylmethyl]-2-phenyl- 12) and acetamide phenyl-acetyl chloride 64 396.51 N-[6-(4-cyclopentyl- C-[6-(4-cyclopentyl-piperazin-1-yl)- 397.4 piperazin-1-yl)-pyridin-3- pyridin-3-yl]-methylamine (intermediate ylmethyl]-2-(4-fluoro- 12) and phenyl)-acetamide (4-fluoro-phenyl)-acetyl chloride 65 352.5 ethanesulfonic acid [6-(4- C-[6-(4-cyclopentyl-piperazin-1-yl)- 353.3 cyclopentyl-piperazin-1-yl)- pyridin-3-yl]-methylamine (intermediate pyridin-3-ylmethyl]-amide 12) and ethanesulfonyl chloride 66 366.53 propane-1-sulfonic acid [6- C-[6-(4-cyclopentyl-piperazin-1-yl)- 367.2 (4-cyclopentyl-piperazin-1- pyridin-3-yl]-methylamine (intermediate yl)-pyridin-3-ylmethyl]- 12) and amide propanesulfonyl chloride 67 367.52 N-[6-(4-cyclopentyl- C-[6-(4-cyclopentyl-piperazin-1-yl)- 368.2 piperazin-1-yl)-pyridin-3- pyridin-3-yl]-methylamine (intermediate ylmethyl]- 12) and benzenesulfonamide dimethylaminosulfamoylchloride 68 400.54 N-[6-(4-cyclopentyl- C-[6-(4-cyclopentyl-piperazin-1-yl)- 401.5 piperazin-1-yl)-pyridin-3- pyridin-3-yl]-methylamine (intermediate ylmethyl]- 12) and benzenesulfonamide benzenesulfonyl chloride 69 414.57 N-[6-(4-cyclopentyl- C-[6-(4-cyclopentyl-piperazin-1-yl)- 415.4 piperazin-1-yl)-pyridin-3- pyridin-3-yl]-methylamine (intermediate ylmethyl]-C-phenyl- 12) and methanesulfonamide phenyl-methanesulfonyl chloride 70 449.02 C-(4-chloro-phenyl)-N-[6- C-[6-(4-cyclopentyl-piperazin-1-yl)- 449.3 (4-cyclopentyl-piperazin-1- pyridin-3-yl]-methylamine (intermediate yl)-pyridin-3-ylmethyl]- 12) and methanesulfonamide 4-chloro-phenyl-methanesulfonyl chloride 71 418.53 N-[6-(4-cyclopentyl- C-[6-(4-cyclopentyl-piperazin-1-yl)- 419.3 piperazin-1-yl)-pyridin-3- pyridin-3-yl]-methylamine (intermediate ylmethyl]-2-fluoro- 12) and benzenesulfonamide 2-fluoro-benzenesulfonyl chloride 72 418.53 N-[6-(4-cyclopentyl- C-[6-(4-cyclopentyl-piperazin-1-yl)- 419.3 piperazin-1-yl)-pyridin-3- pyridin-3-yl]-methylamine (intermediate ylmethyl]-3-fluoro- 12) and benzenesulfonamide 3-fluoro-benzenesulfonyl chloride 73 418.53 N-[6-(4-cyclopentyl- C-[6-(4-cyclopentyl-piperazin-1-yl)- 419.3 piperazin-1-yl)-pyridin-3- pyridin-3-yl]-methylamine (intermediate ylmethyl]-4-fluoro- 12) and benzenesulfonamide 4-fluoro-benzenesulfonyl chloride 74 434.99 2-chloro-N-[6-(4- C-[6-(4-cyclopentyl-piperazin-1-yl)- 435.3 cyclopentyl-piperazin-1-yl)- pyridin-3-yl]-methylamine (intermediate pyridin-3-ylmethyl]- 12) and benzenesulfonamide 2-chloro-benzenesulfonyl chloride 75 434.99 4-chloro-N-[6-(4- C-[6-(4-cyclopentyl-piperazin-1-yl)- 435.3 cyclopentyl-piperazin-1-yl)- pyridin-3-yl]-methylamine (intermediate pyridin-3-ylmethyl]- 12) and benzenesulfonamide 4-chloro-benzenesulfonyl chloride 76 371.46 1-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 372.3 yl)-pyridin-3-ylmethyl]-3-(4- yl]-methylamine (intermediate 10) and fluoro-benzyl)-urea 1-fluoro-4-isocyanatomethyl-benzene 77 354.45 N-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 355.3 yl)-pyridin-3-ylmethyl]-3- yl]-methylamine (intermediate 10) and methoxy-benzamide 3-methoxybenzoylchloride 78 338.45 N-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 339.2 yl)-pyridin-3-ylmethyl]-2- yl]-methylamine (intermediate 10) and phenyl-acetamide phenyl-acetyl chloride 79 356.44 N-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 357.3 yl)-pyridin-3-ylmethyl]-2-(4- yl]-methylamine (intermediate 10) and fluoro-phenyl)-acetamide 4-fluoro-phenyl acetyl chloride 80 312.44 ethanesulfonic acid [6-(4- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 313 ethyl-piperazin-1-yl)- yl]-methylamine (intermediate 10) and pyridin-3-ylmethyl]-amide ethanesulfonylchloride 81 326.46 propane-1-sulfonic acid [6- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 327.3 (4-ethyl-piperazin-1-yl)- yl]-methylamine (intermediate 10) and pyridin-3-ylmethyl]-amide propanesulfonylchloride 82 327.45 N-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 328.2 yl)-pyridin-3-ylmethyl]- yl]-methylamine (intermediate 10) and dimethylaminosulfonamide dimethylaminosulfamoylchloride 83 360.48 N-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 361.3 yl)-pyridin-3-ylmethyl]- yl]-methylamine (intermediate 10) and benzenesulfonamide benzenesulfonyl chloride 84 374.51 N-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 375.4 yl)-pyridin-3-ylmethyl]-C- yl]-methylamine (intermediate 10) and phenyl-methanesulfonamide phenyl-methanesulfonyl chloride 85 408.95 C-(4-Chloro-phenyl)-N-[6- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 409.3 (4-ethyl-piperazin-1-yl)- yl]-methylamine (intermediate 10) and pyridin-3-ylmethyl]- 4-chloro-phenyl-methanesulfonyl methanesulfonamide chloride 86 378.47 N-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 379.3 yl)-pyridin-3-ylmethyl]-2- yl]-methylamine (intermediate 10) and fluoro-benzenesulfonamide 2-fluoro-benzenesulfonyl chloride 87 378.47 N-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 379.3 yl)-pyridin-3-ylmethyl]-3- yl]-methylamine (intermediate 10) and fluoro-benzenesulfonamide 3-fluoro-benzenesulfonyl chloride 88 378.47 N-[6-(4-ethyl-piperazin-1- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 379.3 yl)-pyridin-3-ylmethyl]-4- yl]-methylamine (intermediate 10) and fluoro-benzenesulfonamide 4-fluoro-benzenesulfonyl chloride 89 394.92 2-chloro-N-[6-(4-ethyl- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 395.3 piperazin-1-yl)-pyridin-3- yl]-methylamine (intermediate 10) and ylmethyl]- 2-chloro-benzenesulfonyl chloride benzenesulfonamide 90 394.92 4-chloro-N-[6-(4-ethyl- C-[6-(4-ethyl-piperazin-1-yl)-pyridin-3- 395.3 piperazin-1-yl)-pyridin-3- yl]-methylamine (intermediate 10) and ylmethyl]- 4-chloro-benzenesulfonyl chloride benzenesulfonamide

Example 91 4-Methyl-piperidine-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide

A mixture of 29 mg (0.08 mmol) [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-carbamic acid phenyl ester (intermediately built from intermediate 6 and phenylchloroformate) and 12 mg (0.12 mmol) 4-methyl-piperidine (commercially available) in 1 ml DCM and 0.1 ml DMF was stirred at room temperature for 16 h. After evaporation the residue was taken up in methanol/DMF and subjected to preparative HPLC purification on reversed phase eluting with a gradient of acetonitrile/water (0.05% triethylamine). The combined product fractions were evaporated to dryness to yield 13.6 mg (46%) of the title compound. (m/e): 372.3 (MH⁺; 100%).

Example 92 2,6-Dimethyl-piperidine-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 2,6-dimethyl-piperidine-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide was synthesized from intermediate 6 and 2,6-dimethyl-piperidine (commercially available). (m/e): 372.3 (MH⁺; 100%).

Example 93 4-Trifluoromethyl-piperidine-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 4-trifluoromethyl-piperidine-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide was synthesized from intermediate 6 and 4-trifluoromethyl-piperidine (commercially available). (m/e): 426.3 (MH⁺; 100%).

Example 94 1-[6-(4-Cyclopentyl-piperazin-1-yl)-pyridin-3-ylcarbamoyl]-piperidine-4-carboxylic acid ethyl ester

According to the procedure described for the synthesis of Example 91 1-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylcarbamoyl]-piperidine-4-carboxylic acid ethyl ester was synthesized from intermediate 6 and piperidine-4-carboxylic acid ethyl ester (commercially available). (m/e): 430.4 (MH⁺; 100%).

Example 95 Octahydro-quinoline-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 octahydro-quinoline-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide was synthesized from intermediate 6 and 2,6-dimethyl-piperidine (commercially available). (m/e): 412.5 (MH⁺; 100%).

Example 96 Octahydro-isoquinoline-2-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 octahydro-isoquinoline-2-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide was synthesized from intermediate 6 and octahydro-isoquinoline (commercially available). (m/e): 412.5 (MH⁺; 100%).

Example 97 2-trifluoromethyl-pyrrolidine-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 2-trifluoromethyl-pyrrolidine-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]amide was synthesized from intermediate 6 and 2-trifluoromethyl-pyrrolidine (commercially available). (m/e): 412.4 (MH⁺; 100%).

Example 98 2-Isopropyl-pyrrolidine-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 2-isopropyl-pyrrolidine-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide was synthesized from intermediate 6 and 2-isopropyl-pyrrolidine (commercially available). (m/e): 386.3 (MH⁺; 100%).

Example 99 1,3-Dihydro-isoindole-2-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 1,3-dihydro-isoindole-2-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide was synthesized from intermediate 6 and 1,3-dihydro-isoindole (commercially available). (m/e): 392.2 (MH⁺; 100%).

Example 100 3-[6-(4-Cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-1-isopropyl-1-(2-methoxy-ethyl)-urea

According to the procedure described for the synthesis of Example 91 3-[6-(4-Cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-1-isopropyl-1-(2-methoxy-ethyl)-urea was synthesized from intermediate 6 and isopropyl-2-methoxyethyl-amine (commercially available). (m/e): 390.4 (MH⁺; 100%).

Example 101 Azepane-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 azepane-1-carboxylic acid [6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]amide was synthesized from intermediate 6 and azepine (commercially available). (m/e): 372.3 (MH⁺; 100%).

Example 102 3-[6-(4-Cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-1-ethyl-1-phenyl-urea

According to the procedure described for the synthesis of Example 91 3-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-1-ethyl-1-phenyl-urea was synthesized from intermediate 6 and ethylphenylamine (commercially available). (m/e): 394.4 (MH⁺; 100%).

Example 103 3-[6-(4-Cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-1-(4-methoxy-phenyl)-1-methyl-urea

According to the procedure described for the synthesis of Example 91 3-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-yl]-1-(4-methoxy-phenyl)-1-methyl-urea was synthesized from intermediate 6 and (4-methoxy-phenyl)-methyl-amine (commercially available). (m/e): 410.4 (MH⁺; 100%).

Example 104 3,4-Dihydro-2H-quinoline-1-carboxylic acid [6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 3,4-dihydro-2H-quinoline-1-carboxylic acid [6-(4-ethyl-piperazin-1-yl)-pyridin-3-yl]-amide was synthesized from intermediate 2 and 3,4-dihydro-2H-quinoline (commercially available). (m/e): 366.3 (MH⁺; 100%).

Example 105 3,4-Dihydro-2H-quinoline-1-carboxylic acid [6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-amide

According to the procedure described for the synthesis of Example 91 3,4-dihydro-2H-quinoline-1-carboxylic acid [6-(4-isopropyl-piperazin-1-yl)-pyridin-3-yl]-amide was synthesized from intermediate 4 and 3,4-dihydro-2H-quinoline (commercially available). (m/e): 380.3 (MH⁺; 100%).

Example 106

Film coated tablets containing the following ingredients can be manufactured in a conventional manner:

Ingredients Per tablet Kernel: Compound of formula (I) 10.0 mg  200.0 mg  Microcrystalline cellulose 23.5 mg  43.5 mg  Lactose hydrous 60.0 mg  70.0 mg  Povidone K30 12.5 mg  15.0 mg  Sodium starch glycolate 12.5 mg  17.0 mg  Magnesium stearate 1.5 mg 4.5 mg (Kernel Weight) 120.0 mg  350.0 mg  Film Coat: Hydroxypropyl methyl cellulose 3.5 mg 7.0 mg Polyethylene glycol 6000 0.8 mg 1.6 mg Talc 1.3 mg 2.6 mg Iron oxide (yellow) 0.8 mg 1.6 mg Titanium dioxide 0.8 mg 1.6 mg

The active ingredient is sieved and mixed with microcrystalline cellulose and the mixture is granulated with a solution of polyvinylpyrrolidone in water. The granulate is mixed with sodium starch glycolate and magnesium stearate and compressed to yield kernels of 120 or 350 mg respectively. The kernels are lacquered with an aqueous solution/suspension of the above mentioned film coat.

Example 107

Capsules containing the following ingredients can be manufactured in a conventional manner:

Ingredients Per capsule Compound of formula (I) 25.0 mg Lactose 150.0 mg  Maize starch 20.0 mg Talc  5.0 mg

The components are sieved and mixed and filled into capsules of size 2.

Example 108

Injection solutions can have the following composition:

Compound of formula (I) 3.0 mg Gelatine 150.0 mg Phenol 4.7 mg Sodium carbonate to obtain a final pH of 7 Water for injection solutions ad 1.0 ml

Example 109

Soft gelatin capsules containing the following ingredients can be manufactured in a conventional manner:

Capsule contents Compound of formula (I) 5.0 mg Yellow wax 8.0 mg Hydrogenated Soya bean oil 8.0 mg Partially hydrogenated plant oils 34.0 mg Soya bean oil 110.0 mg Weight of capsule contents 165.0 mg Gelatin capsule Gelatin 75.0 mg Glycerol 85% 32.0 mg Karion 83 8.0 mg (dry matter) Titanium dioxide 0.4 mg Iron oxide yellow 1.1 mg

The active ingredient is dissolved in a warm melting of the other ingredients and the mixture is filled into soft gelatin capsules of appropriate size. The filled soft gelatin capsules are treated according to the usual procedures.

Example 110

Sachets containing the following ingredients can be manufactured in a conventional manner:

Compound of formula (I) 50.0 mg Lactose, fine powder 1015.0 mg  Microcrystalline cellulose (AVICEL PH 102) 1400.0 mg  Sodium carboxymethyl cellulose 14.0 mg Polyvinylpyrrolidone K 30 10.0 mg Magnesium stearate 10.0 mg Flavoring additives  1.0 mg

The active ingredient is mixed with lactose, microcrystalline cellulose and sodium carboxymethyl cellulose and granulated with a mixture of polyvinylpyrrolidone in water. The granulate is mixed with magnesium stearate and the flavoring additives and filled into sachets.

Example 111

The following test was carried out in order to determine the activity of the compounds of formula (I).

Binding Assay with ³H-(R)α-methylhistamine

Saturation binding experiments were performed using HR3-CHO membranes prepared as described in Takahashi, K, Tokita, S., Kotani, H. (2003) J. Pharmacol. Exp. Therapeutics 307, 213-218.

An appropriate amount of membrane (60 to 80 μg protein/well) was incubated with increasing concentrations of ³H(R)α-Methylhistamine di-hydrochloride (0.10 to 10 nM). Non specific binding was determined using a 200 fold excess of cold (R)α-Methylhistamine dihydrobromide (500 nM final concentration). The incubation was carried out at room temperature (in deep-well plates shaking for three hours). The final volume in each well was 250 μl. The incubation was followed by rapid filtration on GF/B filters (pre-soaked with 100 μl of 0.5% PEI in Tris 50 mM shaking at 200 rpm for two hours). The filtration was made using a cell-harvester and the filter plates were then washed five times with ice cold washing buffer containing 0.5 M NaCl. After harvesting, the plates were dried at 55° C. for 60 min, then we added scintillation fluid (Microscint 40, 40 microl in each well) and the amount of radioactivity on the filter was determined in Packard top-counter after shaking the plates for two hours at 200 rpm at room temperature.

Binding Buffer: 50 mM Tris-HCl pH 7.4 and 5 mM MgCl₂x6H₂O pH 7.4. Washing Buffer: 50 mM Tris-HCl pH 7.4 and 5 mM MgCl₂x6H₂O and 0.5 M NaCl pH 7.4.

Indirect measurement of affinity of H3R inverse agonists: twelve increasing concentrations (ranging from 10 μM to 0.3 nM) of the selected compounds were always tested in competition binding experiments using membrane of the human HR3-CHO cell line. An appropriate amount of protein, e.g. approximately 500 cpm binding of RAMH at Kd, were incubated for 1 hour at room temperature in 250 μl final volume in 96-well plates in presence of ³H(R)α-Methylhistamine (1 nM final concentration=Kd). Non-specific binding was determined using a 200 fold excess of cold (R)α-Methylhistamine dihydrobromide.

All compounds were tested at a single concentration in duplicates. Compounds that showed an inhibition of [³H]-RAMH by more than 50% were tested again to determine IC₅₀ in a serial dilution experiment. Ki's were calculated from IC₅₀ based on Cheng-Prusoff equation (Cheng, Y, Prusoff, W H (1973) Biochem Pharmacol 22, 3099-3108).

The compounds of the present invention exhibit K_(i) values within the range of about 1 nM to about 1000 nM, preferably of about 1 nM to about 100 nM, and more preferably of about 1 nM to about 30 nM. The following table shows measured values for some selected compounds of the present invention.

The following table shows measured values for some selected compounds of the present invention:

K_(i) (nM) Example 3 39 Example 34 81 Example 53 40

It is to be understood that the invention is not limited to the particular embodiments of the invention described above, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. 

1. A compound of formula I or a pharmaceutically acceptable salt thereof wherein formula I is:

wherein: (a) R¹ is selected from the group consisting of: (1) lower alkyl, and (2) C₃-C₇-cycloalkyl (b) X is C(O); (c) m is 1; (d) R² is selected from the group consisting of: (1) lower alkyl, (2) C₃-C₇-alkenyl, (3) C₃-C₇-alkinyl, (4) lower halogenalkyl, (5) lower hydroxyalkyl, (6) lower alkoxyalkyl, (7) unsubstituted C₃-C₇-cycloalkyl or C₃-C₇-cycloalkyl substituted by phenyl, (8) lower C₃-C₇-cycloalkylalkyl, (9) lower phenylalkyl wherein said phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, (10) unsubstituted pyridyl or pyridyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, (11) —NR³R⁴, (12) lower alkoxy, and (13) lower alkoxyalkoxy or alternatively, R² can also be unsubstituted phenyl or phenyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, (e) R³ is hydrogen or lower alkyl; and R⁴ is selected from the group consisting of: (1) lower alkyl, (2) C₃-C₇-alkenyl, (3) C₃-C₇-alkinyl, (4) lower alkoxyalkyl, (5) C₃-C₇-cycloalkyl, (6) C₃-C₇-cycloalkyl substituted by phenyl, (7) lower C₃-C₇-cycloalkylalkyl, (8) unsubstituted phenyl or phenyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, and (9) lower phenylalkyl wherein phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl; or alternatively, R³ and R⁴ together with the nitrogen atom to which they are attached form a 4-, 5-, 6- or 7-membered heterocyclic ring optionally containing a further heteroatom of nitrogen, oxygen or sulfur, wherein said heterocyclic ring is optionally substituted by one, two or three groups independently selected from the group consisting of lower alkyl, lower alkoxy, lower alkoxycarbonyl, oxo, halogen and halogenalkyl, or said heterocyclic ring is optionally condensed with a C₅-C₆-cycloalkyl ring or a phenyl ring, wherein said cycloalkyl ring or phenyl ring is optionally substituted by one, two or three groups independently selected from the group consisting of lower alkyl, lower alkoxy, halogen and halogenalkyl.
 2. A compound according to claim 1, wherein R¹ is C₃-C₇-cycloalkyl.
 3. A compound according to claim 1, wherein R¹ is ethyl or isopropyl.
 4. A compound according to claim 1, wherein R² is selected from the group consisting of: (1) lower alkyl, (2) C₃-C₇-alkenyl, (3) C₃-C₇-alkinyl, (4) lower halogenalkyl, (5) lower hydroxyalkyl, (6) lower alkoxyalkyl, (7) unsubstituted C₃-C₇-cycloalkyl or C₃-C₇-cycloalkyl substituted by phenyl, (8) lower C₃-C₇-cycloalkylalkyl, (9) lower phenylalkyl wherein said phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, (10) unsubstituted pyridyl or pyridyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, and (11) —NR³R⁴, or alternatively, R² can also be lower alkoxy or lower alkoxyalkoxy.
 5. A compound according to claim 1, wherein R² is selected from the group consisting of lower alkyl, C₃-C₇-cycloalkyl and C₃-C₇-cycloalkyl substituted by phenyl.
 6. A compound according to claim 1, wherein R² is lower phenylalkyl wherein said phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl.
 7. A compound according to claim 1, wherein R² is —NR³R⁴ and R³ and R⁴ are as defined in claim
 1. 8. A compound according to claim 1, wherein R³ is hydrogen or lower alkyl; and R⁴ is selected from the group consisting of: (1) lower alkyl, (2) C₃-C₇-alkenyl, (3) C₃-C₇-alkinyl, (4) C₃-C₇-cycloalkyl, (5) C₃-C₇-cycloalkyl substituted by phenyl, (6) lower C₃-C₇-cycloalkylalkyl, (7) unsubstituted phenyl or phenyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, and (8) lower phenylalkyl wherein said phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl; or alternatively, R³ and R⁴ together with the nitrogen atom to which they are attached form a 4-, 5-, 6- or 7-membered heterocyclic ring optionally containing a further heteroatom of nitrogen, oxygen or sulfur, said heterocyclic ring is optionally substituted by one, two or three groups independently selected from the group consisting of lower alkyl, lower alkoxy, oxo, halogen and halogenalkyl, or said heterocyclic ring is optionally condensed with a phenyl ring, wherein said phenyl ring is optionally substituted by one, two or three groups independently selected from the group consisting of lower alkyl, lower alkoxy, halogen and halogenalkyl.
 9. A compound according to claim 1, wherein R³ and R⁴ are lower alkyl.
 10. A compound according to claim 7, wherein R³ is hydrogen and R⁴ is selected from the group consisting of: (1) lower alkyl, (2) C₃-C₇-alkenyl, (3) C₃-C₇-alkinyl, (4) C₃-C₇-cycloalkyl, (5) C₃-C₇-cycloalkyl substituted by phenyl, (6) lower C₃-C₇-cycloalkylalkyl, (7) unsubstituted phenyl or phenyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, and (8) lower phenylalkyl wherein said phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl.
 11. A compound according to claim 7, wherein R³ is hydrogen and R⁴ is lower phenylalkyl wherein said phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl.
 12. A compound according to claim 1, wherein R² is unsubstituted phenyl or phenyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl.
 13. A compound according to claim 1, wherein R² is —NR³R⁴.
 14. A compound according to claim 1, selected from the group consisting of: N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-butyramide, N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-methoxy-benzamide, N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-phenyl-acetamide, N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-(4-fluoro-phenyl)-acetamide, 1-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-(4-fluoro-benzyl)-urea, N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-methoxy-benzamide, N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-phenyl-acetamide, N-[6-(4-ethyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-(4-fluoro-phenyl)-acetamide, and pharmaceutically acceptable salts thereof.
 15. A compound according to claim 1, selected from the group consisting of: N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-3-methoxy-benzamide, N-[6-(4-cyclopentyl-piperazin-1-yl)-pyridin-3-ylmethyl]-2-phenyl-acetamide, and pharmaceutically acceptable salts thereof.
 16. A process for the manufacture of a compound according to claim 1, comprising the steps of: a) reacting a compound of the formula II

wherein R¹ and m are as defined in claim 1, with a chloride of the formula IV R²—C(O)Cl  IV wherein R² is as defined in claim 1, to obtain a compound of the formula I-B

wherein R¹, R² and mare as defined in claim 1, or b) reacting a compound of the formula II

wherein R¹ and m are as defined in claim 1, with an isocyanate of the formula V R⁴—N═C═O  V wherein R⁴ is as defined in claim 1, to obtain a compound of the formula I-C

wherein R³ is hydrogen and R¹, R⁴ and m are as defined in claim 1, and if desired, converting the compound of formula I-B or I-C into a pharmaceutically acceptable salt.
 17. A pharmaceutical composition, comprising a therapeutically effective amount of a compound according to claim 1 and a pharmaceutically acceptable carrier and/or adjuvant.
 18. A compound of formula I or a pharmaceutically acceptable salt thereof wherein formula I is:

wherein: (a) R¹ is selected from the group consisting of: (1) lower alkyl, and (2) C₃-C₇-cycloalkyl (b) X is C(O): (c) m is 1; (d) R² is selected from the group consisting of: (1) lower alkyl, (2) C₃-C₇-alkenyl, (3) C₃-C₇-alkinyl, (4) lower halogenalkyl, (5) lower hydroxyalkyl, (6) lower alkoxyalkyl, (7) unsubstituted C₃-C₇-cycloalkyl or C₃-C₇-cycloalkyl substituted by phenyl, (8) lower C₃-C₇-cycloalkylalkyl, (9) lower phenylalkyl wherein said phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl. (10) unsubstituted pyridyl or pyridyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, (11) lower alkoxy, and (12) lower alkoxyalkoxy or alternatively, R² can also be unsubstituted phenyl or phenyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, (e) R³ is hydrogen or lower alkyl; and R⁴ is selected from the group consisting of: (1) lower alkyl, (2) C₃-C₇-alkenyl, (3) C₃-C₇-alkinyl, (4) lower alkoxyalkyl, (5) C₃-C₇-cycloalkyl, (6) C₃-C₇-cycloalkyl substituted by phenyl, (7) lower C₃-C₇-cycloalkylalkyl, (8) unsubstituted phenyl or phenyl mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl, and (9) lower phenylalkyl wherein phenyl is unsubstituted or mono- or disubstituted by lower alkyl, lower alkoxy, halogen or lower halogenalkyl; or alternatively, R³ and R⁴ together with the nitrogen atom to which they are attached form a 4-, 5-, 6- or 7-membered heterocyclic ring optionally containing a further heteroatom of nitrogen, oxygen or sulfur, wherein said heterocyclic ring is optionally substituted by one, two or three groups independently selected from the group consisting of lower alkyl, lower alkoxy, lower alkoxycarbonyl, oxo, halogen and halogenalkyl, or said heterocyclic ring is optionally condensed with a C₅-C₆-cycloalkyl ring or a phenyl ring, wherein said cycloalkyl ring or phenyl ring is optionally substituted by one, two or three groups independently selected from the group consisting of lower alkyl, lower alkoxy, halogen and halogenalkyl. 